Tiltable counter-rotating rotor system for helicopters and control means therefor



x l. B. LASKOWITZ TILTABLE COUNTER-ROTATING ROTOR S Jam-l3, 1948.

HELICOPTERS AND CONTROL MEANS Filed Jan. 6, 1943 IN VENTOR.

Y E R m T A I. B. LASKOWITZ TILTABLE COUNTER- Jan. 13, 14,

ROTATING ROTOR" SYSTEM FOR HELICOPTERS AND CONTROL MEANS THEREFOR Filed Jan. 6, 1943 2 Sheets-Sheet 2 INVENTOR.

A TToyfY IsiDoR B. LASKOWITZ Patented Jan. 13, 1948 TILTABLE COUNTER-ROTATING ROTOR SYSTEM FOR HELICOPTERS AND CON TROL MEANS THEREFOR Isidor B. Laskowitz, Brooklyn, N. Y. Application January 6, 1943, Serial No. 471,492

7 Claims. I

This invention relates to tiltable counter-rotating rotor system for helicopters and control means therefor especially as it may be applied to aircraft and particularly to that type known as helicopters.

It is a primary object of this invention to provide such a mechanism as will readily and easily provide for ascent, descent, movement to the right or left, forward or rearward of the aircraft; provide for hovering or suspension in the air without movement relative to the ground; provide controlling or adjusting mechanism for maintaining lateral balance or stability and for maintaining longitudinal balance or stability; provide for steering movement about the Vertical axis of the aircraft; provide for autorotation of the lift mechanism by providing free-wheeling" thereof should the prime mover or motor fail, thus efiecting descent safely without power in case such an emergency should arise.

Another object of the invention is to provide a mechanism and arrangement having all the qualifications above noted and yet be of such a compact nature as to occupy a small operating area horizontally eliminating all external surfacesor devices except for rotors which control the movement of or stationary condition of the aircraft.

A further object of the invention resides in the provision of variable thrust mechanism by means of which the direction of thrust may be varied to provide a vertical and horizontal component in any direction of the compass without rotation of the aircraft about its vertical axis.

Another object of the invention contemplates a variable thrust mechanism whereby direction of thrust may be varied to provide a vertical and horizontal component in any direction of the compass and concurrently effect control, at will, movement of the aircraft about its vertical axis for steering movement either clockwise or counterclockwise.

A further object is to provide a variable thrust mechanism embodying a pair of coaxially arranged rotors moving in opposite directions whereby to normally balance out the reaction torques set up by each rotor and yet, at will, vary the speed of one rotor with respect to the other to the extent that the reaction may difier to establish desired control of the aircraft.

Another important object of the invention is to embody the features of a variable thrust mechanism having the qualities set out above which will be relatively simple in construction yet positive in action, strong and durable with parts arranged to facilitate ready and easy adjustments whenever necessary, thus assuring its practicability.

Other objects and advantages of the present invention will become apparent from the following detailed description of a preferred embodiment of the invention illustrated in the accompanying drawings wherein like reference characters designate corresponding parts throughout the several views and wherein:

Figure 1 is a vertical section of a variable thrust mechanism embodying the invention taken substantially along line ll of Figure 2;

Figure 2 is an elevation of the mechanism;

Figure 3 is a horizontal section taken substantially along the line 3-3 of Figure 1;

Figure 4 is a fragmentary horizontal section taken along the line 4--4 of Figure 1; and

Figure 5 is an enlarged fragmentary elevation of control and operating mechanism employed in the preferred embodiment to effect clockwise and counterclockwise rotation of the mechanism about its vertical axis.

Referring now more particularly to the drawings, the preferred embodiment is illustrated as embodied in a helicopter wherein airfoils, vanes or blades I constructed of any suitable or preferred material constitute the rotors. Each blade is pivotally mounted at its inner end on a pin 2, upper pins Zbeing carried by a collar 3 while a collar 4 carries the pins for the lower rotor. Pivotal movement of the blades about their respective pins below a predetermined angle is controlled by means of flexible tie members or links 5 connected to the blades at 6 and to suitable collars 1 and 8 provided for the upper and lower rotors respectively, by means of pins 9. When rotating, the blades may be in vertical oscillation and one such assumed position is illustrated in dotted lines in Figures 1 and 2.

All parts fixedly secured together are preferably welded to each other although any other preferred method of rigidly securing the members may be employed as desired.

With two sets of rotors preferably employed as illustrated in Figures 1 and 2, the upper rotor is carried by a vertical or upright shaft I 0 rotatably mounted within a tubular member I l which carries the lower rotor, thus providing for coaxial support of the rotors. Shaft I0 extends into and through a, gear housing l2 and is rotatable therein. The lower end of shaft I0 is splined into a sleeve l4 having universal connection with a stub shaft l0 at l3 at its upper end while the lower end has universal connection at I 3' with a sleeve [5 suitably splined with an extension shaft Ill connected by means of universal 13" to a bevel gear "5. Gear 16 meshes with a similar gear I! carried on the drive shaft iii of an engine or motor l9 mounted on the base of the supporting frame 20. A gear bracket 20A is provided for supporting shafts I0 and I8 and bevel gears lii andjl.

An automatic declutching or free-wheeling device 2| of any suitable or preferred type is interposed between engine or motor I9 and bevel gear I! whereby the vertical shaft sections, sleeves and universals are free to rotate-when the engine or motor is not functioning, A standard brake mechanism of any suitable or preferred type (not shown) may be associated with any portion of the vertical driving shafting'to prevent its rotation when desired, or when the engine or motor is not operating. When the engine or motor is operating, power will be transmitted through the ,verticalshafting to; the upper rotor, the latter revolving; at such, speed as may be, desired by the pilot and depending upon the speed decided upon: by merely adjusting the throttle controlling the engine orsetting the-brake hereinbeforenoted; Shaft l0 -is keyed or feathered to gear 22"carried in the gear housing; I2. This gear His-connected by means of idler, gears 23. to gear 24 which is suitablysecured to the tubu-- lar member ll, gears 23 being; carried by pins 25. Gears 22, 23 and; 2,4 are freely rotatable within gear housing l2-and may be submerged in a suitable lubricant; retained in; the housing by cover plates 26. Gear casing l2 may-be retained from verticaldisplacement by thrust collars 21 and 28; carriedby shaft I0 andsleeve II, respectively. It will be obvious; that when shaft in and its associated rotorare rotated in one direction, sleeve H andits respective rotor will be rotated in the opposite direction; through the, medium of the differential gearingdescribed Downwardly directedfrom gear'housing I2; is. an extended cylindrical neckgp0rtion29 carrying pins 30. pivotally mounted-in aigimbalring 3| in turn carrying pins-,32rotatably mountedin-v a tubular member 33. supportedi in aninternal annular seat 34'in'the upperportion of frame 23 constituted by a vertical, tubular extension 20,. Tubular member 33 mayyrotateywithin its an: nular seat 34, and, its lower end isiprovidedwith' an external peripheral worm gear ring35isecuredthereto, A,worm;pini0n 36;-mes hes; w-ith.-ring 35, being carried onahorizontalshaftx3]: A, set-of, beveli gears 38 transmit rotaryv motion to shaft 31 from a vertical shaft 39-,Wherebyrotation ofthe latter shaft will impart rotation to them-.- bular member 33 and such rotationineither direction may betransmitted. as isimparted to shaft 39. It will be understood thatwith tubular member 33 remaining.- stationary, when'the en gine or, motor I9, is operating; the upper and lowerrotors willlrevolveat thesame speed andconsequently the reaction torquesofathe rotors will;

balance each other, thereby. eliminating any tendency for. the mechanismto rotate about .its vertical axis. On the otherhand, with the two sets ofrotors operating under motive power, if tubularmember 33 isrotated in either direction, gear housing l2 will also be rotated thereby correspondingly varyingthe speed of thelower rotor. Thus, it may, be possible toset: up-inthe-lowerrotor a reaction torque which-is greater orless than the reaction torque of the'upper'rotor-and this difference in: the reaction torques will cause the craft to rotate-about its'vertical axis in a clockwise or counterclockwise direction depending upon the directional rotation of shaft 39.

Shaft 39 has rotatably mounted at its lower end, opposed spaced bevel gears 40 (Figures 1, 2 and, more particularly, Figure 5) which are enmeshed with gear 4| driven by the engine or motor l9 through shaft 42 and bevel gear 43 (see Figure 1) driving oif gear. l6. Inner, end faces of gears 40 areprovided with clutching-portions 44 of the frictional or tooth type adapted to be engaged by a slidable clutching member 45 that is keyed or splined on shaft 39, suitably provided at. its outer ends with cooperating corresponding clutching portionscomplementary to portions 44. As illustrated in Figure 5, member 45 is in a neutral position, thus immobilizing shaft 39.

However, should this member 45 be shifted to engage upper bevel gear 40 by means of linkage 41 responding to movement of lever 46, shaft 39 will be caused to move in one direction while shifting, of; lever 46. in; the opposite direction. will cause member. 45r1toen age lower. gear--40; thusimparting, rotation; topshaft, 39- in, the opposite direction. Thus, it willbe seen: that; a simple control has been provided to retain shafti3.9:sta-- tionary or to cause'it to, rotateclockwiseor counterclockwise as thecase. may. be-;. The provision of the pivot point indicatedjn the; ring 3 I together with the provision of; the universal. connection in the vertical or uprightjshafting provides for angular displacement'ofshaft loxfromthe vertical by horizontal shifting of stub; shaft ill: at; point, F causing resultant thrust; due to the inclination imposed upon therotors when the shafting is shifted from the verticalpositionA toany other position such, for. example, as B,-C, D or E; as illustrated. Resultant thrust in position B wouldcause forwardotranslationlof; the craft; in position qlmovement' would be to the rear; in position D, movement: would besidewise to the left; andin positionliLsidewise andto the right. By varying the inclinationfrom; position A to either B; orqC, longitudinal stability or control= may be, had whileshift; to position D' or E pro--- vides for.lateral,stability or control. With rotation of the craft about its vertical axisby meansof rotation of;gearyhousing: I2, stability and control of the craft about all three axes is obtained.-

For the purpose. of moving the stubshaft I0 at point F in a horizontal plane; I. prefer to employ the wheeland rocking bridge control mech anismtogether withroneofithe eccentric brackets: or adjustable bearings more-fully andspecifically described and claimedin U; S: Letters PatentNo. 1,872,758 grantedato .me August 23, 1932; for Variable thrust; mechanism; 7

Briefly, suchlmechanism may-be applied in'the' present disclosure by encircling stub shaft l0'-' at point F with a bearing '48 constituting a part of eccentric bracket 49: The latteris slidably car ried ona slottedmember 53 andmay bemoved from side to side as viewed in Figure 1-by 1-0-- tating shafting or spindles 5 I threaded at its end at 52and extendingthrough a threaded boss-53-- carriedby-the eccentricbracketw. Slotted-member 53' is inturn slidably mountedon a frame member 54secured=to frame'20. This arrangement providesforslateral movement at right angles to the direction ofmovement possible in-Fig ure 1 as will be apparent from Figure 2," suchmovement: being responsive torotation of shaft 55'. Bevel gears- 56- ope-ratively connect shaft 55' with a threaded spindle-51"which-is inturn:a5' sociated with i an internally-threaded-boss' 58 pro: vided in the slotted member 50; Bevel gears 53' provide driving connections between the various sections of the shafting 5i and the shaft 55 for transmitting rotary motion from each section to the next section. Near the ends of upper shaft section 5|, there are provided universal joints 5iA to allow for its inclination whenever the eccentric bracket 49 is moved from side to side. Shaft sections 5i are driven by the hollow shaft 50 by means of bevel gears Bl.

Attached to the inner end of the shaft Fill is an inverted U-shaped rocking bridge 62. A suitable grooved flexible cable drum 63 is mounted at the top of bridge 62 and is adapted to be turned by a hand control wheel G l. Adjacent the bottom portion of the rocking bridge, there are provided a pair of pulleys or guide sheaves MA. Shaft section 55' of the shaft 55 is adapted to extend along the bottom of frame 29 toward the rocking bridge and has a grooved drive pulley 65 secured thereto. A similar grooved pulley 55, but acting only as an idler pulley, is disposed in opposed relation to pulley 65. A flexible cable 66 of wire rope preferably is wound around drum e3, sheaves 64A, through hollow shaft 68 and around pulleys 65 and 65'. The ends of the, cable are preferably secured by a turnbuckle 67 for purposes of adjustment when necessary.

As will be evident, the construction and arrangement is such that by turning control wheel 64 in one direction, the eccentric bracket 49 will move to one side or the other as indicated by the arrows in Figure 2 depending upon the direction of rotation of wheel. Also, by inclining the rocking bridge 62 or dipping it fore and aft, the eccentric bracket is moved in opposite directions at right angles to the previously described movement in the direction of the arrows illustrated in Figure 1. Thus, it is possible to vary the resultant thrust of the mechanism in any direction as hereinbefore described.

Variable thrust mechanism of the character described may be applied to land or water craft or to any other type of craft in which it may be useful. The compactness of the arrangement is such as to readily lend itself to use in a confined area both as to craft and the space which may be available for operation of the craft. It will be clear that all controls are proximately disposed and are of a positive acting nature so as to avoid any element of failure of operation and control. Since the thrust or lift of a single rotor is approximately proportional to the area of rotation of the same, by employing dual rotors in vertical tandem or superposed spaced relation, the required area of operation has been cut approximately in half. Thus, the operating area of the craft is materially reduced as above noted. This is important in taking off and landing in close spaces.

Obviously, minor changes may be made in the preferred embodiment without departing from the essence of the invention or the scope of the appended claims. Thus, ball or roller bearings may be employed in place of the sleeve bearings disclosed. Rigid blades may, of course, be employed in place of the pivoted blades shown. It is contemplated that other equivalent mechanical control movements might be substituted for the ones shown without essentially departing from the spirit of the invention.

Having thus described the invention, what is claimed and desired to be secured by Letters Patentis:

1. A helicopter comprising a supporting frame,

a pair of concentric shafts mounted on said framenism interconnecting said shafts for driving said shafts in opposite directions, means connected to said shafts for Varying the relative speeds of rotation of said shafts, one of said shafts having an extended portion connected by means of a universal joint to a source of power, and a bracket structure connected to said extended portion and mounted for displacement in a plane transverse to the said shafts, said extended portion including universal joints and splined axially slidable connections above and below the point of connection to said bracket structure, whereby tilting of the rotor units may be effected in any desired direction by appropriate displacement of said bracket structure to control and stabilize the helicopter.

2. A helicopter, comprising a supporting frame, a pair of concentric shafts, bladed rotor units secured on said shafts, differential gearing mechanism operatively connected to said shafts whereby said rotor units may be operated in opposite rotary directions, said differential mechanism being connected to said frame by gimbal means for universal tilting movement above said frame, one of said shafts having an extended portion extending downwardly into said frame, in combination with a prime mover located in said frame and connected to said extended portion, said extended portion being provided with a pair of universal joints and splines located between said gimbal means and said prime mover, and a shaft section connecting said pair of universal joints, a bearing embracing said shaft section, said bearing being supported by an adjustable bracket structure, said bracket structure and bearing being mounted to move transversely in any direction relative to said extended portion for simultaneously tilting said concentric shafts and their units, control means connected to said bracket structure to actuate the same to any position of desired adjustment, tubular means connected to said gimbal means and rotatively mounted in said frame to rotate about an upright axis, driving means connected to said tubular means and to said prime mover, a reversible clutch mechanism interposed in said driving means, and means to control said clutch mechanism.

3. A helicopter comprising a supporting frame, a pair of concentric shafts, each of said shafts having a bladed rotor unit secured thereto, a differential gear mechanism interconnected with said shafts for driving said shafts in opposite directions, said gear mechanism being connected to said frame by gimbal means to permit universal tilting movement of said shafts relative to said frame, the inner shaft extending through said gear mechanism and being provided with an extended portion extending into said frame and operatively connected to a prime mover therein, said extended portion having a pair of universal joints and a pair of spaced splined connections, a bearing embracing said extended portion between said splined connections, an adjustable bracket structure secured in said frame and supporting said bearing, said bracket structure and bearing being adjustable transversely in any direction relative to said extended portion, actuating means connected to said bracket to adjust the same to any desired position, and mechanism to control said actuating means, a tubular means rotatively mounted on said frame for receiving topandrcontrol,meanseonnectectto.said.;clutch .t0. 6;

actuate the same.

4; A- helicopter comprisinga supporting; frame;; a pairaof concentric, shafts, each of 1 said: shafts. having a bladed rotor, unit, secured thereto, a,

differential gear mechanism,-interconnectinggsaid; 10L

shafts-for driving; said shafts, insopposite direc tions, .a tubular means rotatively mountedonsaid; frame;.said tubular, means receiving: imbahmeans. and; supporting the same therein, said gimbal:

means; receiving the lower portion of, said gear,

mechanism and supporting said; gear mechanism; to: permit universal tilting movement of, said: shafts relative to said frame, the innershaft. extending through said gear mechanism and be-- ing provided with an extended portion extending,

ing control meanstherefor, and means for. disinto. said frame and operativelyconnected: to; a prime mover in said frame, said extended portion being provided with a shaft section, universal joints and splines connecting said-shaft section.

to the upper and lower portionsof said; innerassembly. including apair of concentric shafts, a

shaft, an additional universal joint interposedin, said inner shaft and located below said. lower spline, an adjustable bracket structure'mounted, in said-frame anddisposed laterally, of saidvshaft,

section, an arm on saidbracket structure, said.

arm having a bearing thereon embracing said shaft section, means connectedto; said. bracket. structure for shifting said bearing and shaftsection transversely of the axis of said inner shaft, and means for controlling; said, said tubular means being operatively, connected, with driving means therefor, a reversible clutch; mechanism for operatively-connecting saiddriving means to said prime mover, and. additional.

means connected to said clutch. mechanism for o controllingthe same.

5. Ahelicopter comprisingasupporting frame, a pair of concentric shafts mounted on. said. frame for. universal tilting. movementwith relae tion thereto, eachof, said shafts havinga bladed.

rotor unit secured thereto,.a.gear. mechanisminterconnecting said. shafts for. drivingsaidishafts. in, opposite directions, means. connected. to,. the. outer shaft to vary the speed',of.'the. outersshaft.

relativeto the speedof the inner shaft, theinner shaft having an extendedportionextendinginto. said frameandconnectedtoa prime mover,therein,. said extended portion having universal joints andspaced splined1 connections thereon, adjust-1 ablemeans connected ti'on whereby the adjacent section of said portion maybe shifted transversely of; the axis of'the, inner shaft. to effect tilting, of said shafts, and means connected to, said adjustable means to con-.- trol the shifting thereof.

6; A helicopter. comprising a supportingframe 6 a pair of concentric, shafts, each ofsaid' shafts. having, a bladed rotor unit secured thereto, a gear, mechanism interconnecting said shafts for drivingsaidshafts in opposite directions, a prime mover located in said frame, the inner shaft extendingthrough said gear mechanism. and havingan extendedportion extending into saidframe. and connected to. said prime mover, said outer shifting means,

shaft.- and gear. mechanism: being; connected to;

said frame:.by: gimbal means. to: permit: universal;

tilting movement; .of; said: shafts: relative to; said. frame,-said gimbaLmeans-having aztubular outer ring rotatively. supportedin said frame. saidexe tended, portion .being;pr.ovided with ashaft section interposedtherein and connected thereto by uni.- versal joints and splines, an additional universal joint being also interposed below. the lower spline; in said-extendedportion, a. bearing embracing saidshaft section,-said bearing-having mounting; means therefor in said frame for transverse-adjustmentin any direction relative to said shafts, control'means connectedto said mounting means. to actuatesaid mounting means in any-direction transversely of saidshaft. section, saidjouter ring. beingprovidedwith a..worm wheelon the. exterior, lower, portion, thereof, said worm wheel having: operative;connectiontosaid prime mover, revers-i ing means interposed insaid connection includengaging said prime mover, upon failure thereof, andjthereby. providefor descent safely of said; helicopter.

7. A helicopter comprising a, frame, a. shaft,

pair ofsuperposed spaced rotors secured respectively on said shafts, said frame having side, top andbottom walls, said top-wall having a cen- .tr ally disposed opening i combination with a. tubular portion having an open lower end, said tubular portion beingdisposed over said open;- ing and fixedly secured" thereto, gimbal means anchored and supported in the-upper end of said tubular portion, said gimbal means embracing;

" and supporting theconcentric shaft assembly; a

to. said extended shaft1p.or-

differential housingmounted on said shaft assembly, said housing containing a differential gear mechanism interconnecting said shafts, whereby I rotation of the inner'shaft will rotate the outer shaft in an opposite'direction, the-outer ring of said gimbal means havin means for supporting it rotatively within said tubular, portion, saidouter ring also having a depending portion, said depending portionbeing provided onits outer surfacewitha worm wheel, a prime mover on the; bottom wall aforesaid, drive means forming a; connection with said worm: wheel and'said prime mover; a reversing mechanism: interposed in said. drivemeans whereby said:housing may be A driven: selectively in either of: two directionsto vary the; relative speeds of rotation ofthe concentric, shafts;

ISIDOR B. LASKOWITL.

REFERENCES CITED.

'The following references; are of record-in thefile' of: this: patent:

UNITED. STATES PATENTS Number Name Date 1,014,643 Donnelly Jan, 16, 1912 1,055,533 Highland Mar. 11,1913. 1,578,833 Kogler Mar. 30, 1926 1,788,218 Wettstein Jan, 6, 1931 1,957,813 Wilford May 8, 1,934 2,172,334 Theodorsen et a1. Sept. 5, 1939 1,718,577 Pitcairn June '25,, 1929. 2,352,342, Pitcairn June 27; 19.44 

